The fishBOAT: A swimming watercraft with only one moving part* and no hull penetration.

The non-human version is the fishBOATTM. It is efficient, inexpensive, quiet, capable of extreme depth and can be implemented in craft ranging from toys to massive industrial tugboats. Click here to learn more about it.

A human powered version taught me how to make the fishBOAT. I call the human version the fishBOOTTM.

*Ok, there is more than one moving part. The fluke is also a spring which deflects, which is movement. Certain versions also have a harness, which moves a bit. "One moving part" refers to the torque reaction engine.